Table of contents

12 June 2002, Volume 11 Issue 6 Previous issue    Next issue

GENERAL

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Algebraic structure and Poisson integrals of a rotational relativistic Birkhoff system Luo Shao-Kai (罗绍凯), Chen Xiang-Wei (陈向炜), Guo Yong-Xin (郭永新) Chinese Physics, 2002, 11 (6):  523-528.  DOI: 10.1088/1009-1963/11/6/301 Abstract ( 1299 )   PDF (242KB) ( 549 )   We have studied the algebraic structure of the dynamical equations of a rotational relativistic Birkhoff system. It is proven that autonomous and semi-autonomous rotational relativistic Birkhoff equations possess consistent algebraic structure and Lie algebraic structure. In general, non-autonomous rotational relativistic Birkhoff equations possess no algebraic structure, but a type of special non-autonomous rotational relativistic Birkhoff equation possesses consistent algebraic structure and consistent Lie algebraic structure. Then, we obtain the Poisson integrals of the dynamical equations of the rotational relativistic Birkhoff system. Finally, we give an example to illustrate the application of the results.

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Implementation of nonlocal quantum swap operation on two entangled pairs Zheng Yi-Zhuang (郑亦庄), Gu Yong-Jian (顾永建), Chen Li-Bing (陈立冰), Guo Guang-Can (郭光灿) Chinese Physics, 2002, 11 (6):  529-532.  DOI: 10.1088/1009-1963/11/6/302 Abstract ( 1258 )   PDF (210KB) ( 602 )   We propose a scheme for the implementation of nonlocal quantum swap operation on two spatially separated entangled pairs and we show that the operation can swap two qubits of these entangled pairs. We discuss the resources of the entangled qubits and classical communication bits required for the optimal implementation of the nonlocal quantum swap operation. We also put forward a scheme for probabilistic implementation of nonlocal swap operation via a nonmaximally entangled quantum channel. The probability of a successful nonlocal swap operation is obtained by introducing a collective unitary transformation.

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New multi-soliton solutions and travelling wave solutions of the dispersive long-wave equations Zhang Jie-Fang (张解放), Guo Guan-Ping (郭冠平), Wu Feng-Min (吴锋民) Chinese Physics, 2002, 11 (6):  533-536.  DOI: 10.1088/1009-1963/11/6/303 Abstract ( 1205 )   PDF (277KB) ( 667 )   Using the extended homogeneous balance method, the (1+1)-dimensional dispersive long-wave equations have been solved. Starting from the homogeneous balance method, we have obtained a nonlinear transformation for simplifying a dispersive long-wave equation into a linear partial differential equation. Usually, we can obtain only a type of soliton-like solution. In this paper, we have further found some new multi-soliton solutions and exact travelling solutions of the dispersive long-wave equations from the linear partial equation.

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Teleportation of a three-particle entangled W state Zheng Yi-Zhuang (郑亦庄), Gu Yong-Jian (顾永建), Guo Guang-Can (郭光灿) Chinese Physics, 2002, 11 (6):  537-542.  DOI: 10.1088/1009-1963/11/6/304 Abstract ( 1363 )   PDF (241KB) ( 646 )   We have investigated the problem of teleporting a three-particle entangled W state and we propose a scheme based on entanglement swapping to complete the teleportation. We also put forward a scheme for the teleportation of a general W state by using nonmaximally entangled quantum channels. The probability of success of the latter scheme is obtained.

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Parameter identification and synchronization of an uncertain Chen chaotic system via adaptive control Chen Shi-Hua (陈士华), Zhao Li-Min (赵立民), Liu Jie (刘杰) Chinese Physics, 2002, 11 (6):  543-546.  DOI: 10.1088/1009-1963/11/6/305 Abstract ( 1246 )   PDF (225KB) ( 644 )   A systematic design process of adaptive synchronization and parameter identification of an uncertain Chen chaotic system is provided. With this new and effective method, parameter identification and synchronization of the Chen system, with all the system parameters unknown, can be achieved simultaneously. Theoretical proof and numerical simulation demonstrate the effectiveness and feasibility of the proposed method.

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Bifurcation and solitary waves of the nonlinear wave equation with quartic polynomial potential Hua Cun-Cai (化存才), Liu Yan-Zhu (刘延柱) Chinese Physics, 2002, 11 (6):  547-552.  DOI: 10.1088/1009-1963/11/6/306 Abstract ( 1235 )   PDF (226KB) ( 459 )   For the nonlinear wave equation with quartic polynomial potential, bifurcation and solitary waves are investigated. Based on the bifurcation and the energy integral of the two-dimensional dynamical system satisfied by the travelling waves, it is very interesting to find different sufficient and necessary conditions in terms of the bifurcation parameter for the existence and coexistence of bright, dark solitary waves and shock waves. The method of direct integration is developed to give all types of solitary wave solutions. Our method is simpler than other newly developed ones. Some results are similar to those obtained recently for the combined KdV－mKdV equation.

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Multi-mode q-oscillator algebras with q2(k+1)=1 and related thermo field dynamics Gao Ya-Jun (高亚军) Chinese Physics, 2002, 11 (6):  553-560.  DOI: 10.1088/1009-1963/11/6/307 Abstract ( 1180 )   PDF (298KB) ( 463 )   A type of multi-mode q-oscillator algebra with q2(k+1)=1 is set up and the associated qk-thermo field dynamics is constructed for all k=1,2,…,∞ in a unified form. It is demonstrated that these qk-thermo field dynamics can all be nicely fitted into the algebraic formulation of statistical mechanics (axiomatized form for statistical physics). This means that we obtain infinitely many realizations of the algebraic scheme, which extend the consideration of Ojima [1981 Ann. Phys. 137 1] and contain the usual thermo field dynamics for the fermionic (k=1) and bosonic (k=∞) systems as special cases. As simple applications, the qk-statistical average of some operators are given.

THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

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Solution to the Bargmann－Wigner equation for a half-integral spin Huang Shi-Zhong (黄时中), Ruan Tu-Nan (阮图南), Wu Ning (吴宁), Zheng Zhi-Peng (郑志鹏) Chinese Physics, 2002, 11 (6):  561-567.  DOI: 10.1088/1009-1963/11/6/308 Abstract ( 1111 )   PDF (241KB) ( 486 )   A rigorous method to solve the Bargmann－Wigner equation for an arbitrary half-integral spin is presented and explicit relativistic wavefunctions for an arbitrary half-integral spin are deduced.

ATOMIC AND MOLECULAR PHYSICS

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Formation of the XeI excimer sustained by dielectric barrier discharge in Xe/I2 at low pressure Zhang Lian-Shui (张连水), Zhao Xiao-Hui (赵晓辉), Han Li (韩理) Chinese Physics, 2002, 11 (6):  568-571.  DOI: 10.1088/1009-1963/11/6/309 Abstract ( 1222 )   PDF (188KB) ( 520 )   Dielectric barrier discharge is used to study the mechanism of XeI excimer formation in the mixture of Xe and I2 at low pressures (<1330 Pa). Fluorescence emission in the spectral region of 200－260 nm is examined. We report on the characteristics of the 253 nm emission intensity which varied with different total pressure. The results indicate that under the present experimental conditions, electron impact is the major reaction producing the excimer XeI(B), interpreted as Xe++I2-→XeI(B)+ I*, then radiating 253 nm fluorescence from transition B→X. The 253 nm emission increases with the total gas pressure up to a maximum value at a pressure of about 540 Pa, then decreases as the gas pressure is further increased. The 206 nm emission is determined by I* from ionic recombination between Xe+ and I2-. This result differs from previous works under other experimental conditions.

CLASSICAL AREAS OF PHENOMENOLOGY

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Absorption properties of a driven Doppler-broadened ladder system with hyperfine structure Wu Jin-Hui (吴金辉), Gao Jin-Yue (高锦岳) Chinese Physics, 2002, 11 (6):  572-577.  DOI: 10.1088/1009-1963/11/6/310 Abstract ( 1014 )   PDF (229KB) ( 531 )   We have studied the absorption spectrum of a Doppler-broadened ladder system, where the highest level is coupled into two middle hyperfine sublevels by a strong coherent field. We find that, when the system is considered as homogeneous, either two or three spectral components are observed, depending on the detuning of the coherent field. But when the velocity distribution of atoms is considered, we can always observe one electromagnetically induced transparency (EIT) window with high dispersion. So the atomic hyperfine structure cannot be an impediment for obtaining EIT.

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Effects of pulse chirp on supercontinuum produced in dispersion decreasing fibre Wu Yue (吴越), Lou Cai-Yun (娄采云), Han Ming (韩明), Wang Tong (王桐), Gao Yi-Zhi (高以智) Chinese Physics, 2002, 11 (6):  578-582.  DOI: 10.1088/1009-1963/11/6/311 Abstract ( 1139 )   PDF (224KB) ( 570 )   The supercontinuum (SC) source plays a key role in wavelength division multiplexing over the optical time division multiplexing (WDM/OTDM) transmission system. The SC produced in dispersion decreasing fibre (DDF) is wider and flatter than that produced in dispersion shifted fibre (DSF). In this paper, a SC producing process in DDF is numerically simulated, the effects of pump pulse chirp on the SC width and flatness are initially studied and the corresponding theoretical explanations are given. Particularly, we have analysed and compared the evolutions of the SC along DDF pumped by different chirp pulses. Several valuable conclusions are obtained.

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A new numerical method for the analysis of the permeability anisotropy ratio Xu You-Sheng (许友生), Xu Xian-Zhi (徐献芝) Chinese Physics, 2002, 11 (6):  583-586.  DOI: 10.1088/1009-1963/11/6/312 Abstract ( 1158 )   PDF (209KB) ( 619 )   By combining the lattice Boltzmann method with the three-dimensional computer-simulated images of porous media, a new numerical experimental methodology is used to determine the permeability anisotropy ratio of porous media. The results compare well with the laboratory experimental data.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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Study of the influence of higher-order Laue zones on the exit wavefunction Liu Qiu-Xiang (刘秋香), Yang Qi-Bin (杨奇斌), Wang Yuan-Ming (王元明) Chinese Physics, 2002, 11 (6):  587-591.  DOI: 10.1088/1009-1963/11/6/313 Abstract ( 853 )   PDF (260KB) ( 325 )   Based on an analytical expression of electron dynamical diffraction derived recently, the exit wavefunctions of non-periodic samples have been calculated. The results have shown that the amplitude and phase obtained by the analytical expression were in good agreement with those obtained using the multi-slice method. Besides, the influence of the higher-order Laue zone on the wavefunction for different sample thickness was studied in detail and the results showed that the exit wavefunction is dominated by the zero-order Laue zone. When the sample is very thin, the influence of the higher-order Laue zone should be considered.

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Effects of nickel on the crystallization of Zr70Cu20Ni10 amorphous alloy Wang Huan-Rong (王焕荣), Ye Yi-Fu (叶以富), Zhang Jun-Yan (张均艳), Teng Xin-Ying (滕新营), Min Guang-Hui (闵光辉), Shi Zhi-Qiang (石志强), Tian Xue-Lei (田学雷) Chinese Physics, 2002, 11 (6):  592-595.  DOI: 10.1088/1009-1963/11/6/314 Abstract ( 1304 )   PDF (225KB) ( 523 )   Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) are employed to investigate the effects of nickel on the crystallization of the amorphous Zr70Cu20Ni10 alloy. We have found that the crystallization process of the amorphous Zr70Cu20Ni10 alloy is strongly influenced by the addition of nickel. Addition of 10 at% Ni to the Zr70Cu30 amorphous alloy makes the crystallization process proceed from a single-stage mode to a double-stage mode. The activation energy for crystallization of the amorphous Zr70Cu20Ni10 alloy is calculated to be about 388kJ·mol-1 on the basis of the Kissinger equation. The effects of nickel on the crystallization of the amorphous Zr70Cu20Ni10 alloy are discussed in terms of the genetics of metals.

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Stacking fault energy of cryogenic austenitic steels Dai Qi-Xun (戴起勋), Wang An-Dong (王安东), Cheng Xiao-Nong (程晓农), Luo Xin-Min (罗新民) Chinese Physics, 2002, 11 (6):  596-600.  DOI: 10.1088/1009-1963/11/6/315 Abstract ( 1193 )   PDF (229KB) ( 1935 )   Stacking fault energy and stacking fault nucleation energy are defined in terms of the physical nature of stacking faults and stacking fault energy, and the measuring basis for stacking fault energy. Large quantities of experimental results are processed with the aid of a computer and an expression for calculating stacking fault energy has been obtained as $\gamma$300SF(mJ·m-2)=$\gamma$0SF+1.59Ni-1.34Mn+0.06Mn2-1.75Cr+0.01Cr2+15.21Mo-5.59Si-60.69(C+1.2N)1/2 + 26.27(C+1.2N)(Cr+Mn+Mo)1/2+0.61[Ni·(Cr+Mn)]1/2.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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Optical responses of dilute anisotropic composites: numerical calculations via Green's function formalism Gu Ying (古英), Yu Kin-Wah (余建华) Chinese Physics, 2002, 11 (6):  601-607.  DOI: 10.1088/1009-1963/11/6/316 Abstract ( 1138 )   PDF (284KB) ( 389 )   We investigate the linear and nonlinear optical responses of dilute anisotropic networks using Green's function formalism [Gu Y et al 1999 Phys. Rev. B 59 12847]. For different applied fields, numerical calculations indicate that a large third-order nonlinear enhancement and a broad infrared absorption arise from the geometric anisotropy. We also show the overlap and separation between the absorption peak and nonlinear enhancement peak when the applied field is parallel and perpendicular to the anisotropy, respectively. The results can be understood in terms of the inverse participation ratios with q=2 and the spectral distribution of optical responses.

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Magnetic phase transition and the corresponding magnetostriction of intermetallic compounds RMn2Ge2 (R=Sm, Gd) Guo Guang-Hua (郭光华), Wu Ye (吴烨), Zhang Hai-Bei (张海贝), D A Filippov, R Z Levitin, V V Snegirev Chinese Physics, 2002, 11 (6):  608-612.  DOI: 10.1088/1009-1963/11/6/317 Abstract ( 1160 )   PDF (224KB) ( 495 )   The temperature dependence of lattice constants a and c of intermetallic compounds RMn2Ge2 (R=Sm, Gd) is measured in the temperature range 10－800K by using the x-ray diffraction method. The magnetoelastic anomalies of lattice constants are found at the different kinds of spontaneous magnetic transitions. The transversal and longitudinal magnetostrictions of polycrystalline samples are measured in the pulse magnetic field up to 25T. In the external magnetic field there occurs a first-order field-induced antiferromagnetism－ferromagnetism transition in the Mn sublattice, which gives rise to a large magnetostriction. The magnitude of magnetostrictions is as large as 10-3. The transversal and longitudinal magnetostrictions have the same sign and are almost equal. This indicates that the magnetostriction is isotropic and mainly caused by the interlayer Mn－Mn exchange interaction. The experimental results are explained in the framework of a two-sublattice ferrimagnet with the negative exchange interaction in one of the sublattices by taking into account the lattice constant dependence of interlayer Mn－Mn exchange interaction.

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Spectroscopic properties of Nd-doped phosphate glass with a high emission cross section Mao Yan-Li (毛艳丽), Sun Zhen-Rong (孙真荣), Jiang Xiu-Li (蒋秀丽), Deng Pei-Zhen (邓佩珍), Gan Fu-Xi (干福熹), Chinese Physics, 2002, 11 (6):  613-618.  DOI: 10.1088/1009-1963/11/6/318 Abstract ( 1089 )   PDF (251KB) ( 623 )   Neodymium doped phosphate glasses have been prepared by the semi-continuous melting technique. Their absorption and emission spectra have been recorded at room temperature. The Judd－Ofelt theory has been applied to evaluate the stimulated emission cross sections of 4F3/2→4I11/2 transition for Nd3+. The higher stimulated emission cross section, 4.0×10-20cm2, is obtained. The fluorescence decays of the 4F3/2→4I11/2 transition of Nd3+ are measured for the samples doped (0.7－10) wt% of Nd2O3 at room temperature. The concentration quenching of Nd-doped phosphate glass is mainly attributed to cross-relaxation and energy migration. The site-dependent properties of fluorescence spectra and the fluorescence lifetime of the Nd3+-doped phosphate glass (with 2.2wt%Nd2O3) are studied using laser-induced fluorescence line narrowing techniques, and the site-to-site variations of optical properties are observed at low temperature.

GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS

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The quantum nonthermal effect of a nonstationary Kerr－Newman black hole and the average range of the effective particles Yang Shu-Zheng (杨树政), Lin Li-Bin (林理彬) Chinese Physics, 2002, 11 (6):  619-623.  DOI: 10.1088/1009-1963/11/6/319 Abstract ( 1118 )   PDF (211KB) ( 550 )   We have found that the nonthermal radiation of a nonstationary Kerr－Newman black hole is affected by interstellar materials. In particular, the interstellar gas deeply influences the average range of nonthermal radiation particles, while the average range depends on the maximum energy of the radiation and the energy extent of the radiation.

RAPID COMMUNICATION

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Transport properties under the influence of finite friction Zhan Yong (展永), Zhao Tong-Jun (赵同军), Yu Hui (于慧), Song Yan-Li (宋艳丽) Chinese Physics, 2002, 11 (6):  624-628.  DOI: 10.1088/1009-1963/11/6/320 Abstract ( 1017 )   PDF (224KB) ( 737 )   Using the Langevin Monte Carlo method, the influence of friction on the directed motion of a Brownian particle driven by an external noise source is investigated. The results show that the existence and change of the environment friction influence the establishment and development of the steady motion of a Brownian particle derived by non-equilibrium fluctuation. The most probable correlation time, which corresponds to the maximum current, is inversely proportional to the friction coefficient. The abnormal transition of the current with different friction appears because of the coupling between the effective ratchet potential and coloured noise intensity.

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Investigation of the magnetic domain structure of (PtCoPt)/Si multilayers by magnetic force microscopy Zhang Zhen-Rong (张臻蓉), Liu Hong (刘洪), Han Bao-Shan (韩宝善) Chinese Physics, 2002, 11 (6):  629-634.  DOI: 10.1088/1009-1963/11/6/321 Abstract ( 1038 )   PDF (632KB) ( 577 )   The domain structure of (PtCoPt)/Si multilayers in the dc demagnetized state has been investigated by magnetic force microscopy. The domain structure is found to change dramatically as the thickness of the non-magnetic Si sublayer (tSi) increases. Together with the analysis of magnetic properties, the variation of the domain period indicates that the domain wall energy decreases. Using the model developed by Draaisma and de Jonge, the domain wall energy is obtained.

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Generation of motional cat states for a trapped ion in a cavity Liu Xiang (刘翔), Fang Mao-Fa (方卯发) Chinese Physics, 2002, 11 (6):  635-637.  DOI: 10.1088/1009-1963/11/6/322 Abstract ( 1002 )   PDF (169KB) ( 542 )   Beyond the Lamb－Dicke limit, we propose a simple scheme for generating Schr?dinger cat states of the motion of a trapped two-level ion interacting with a quantized light field in a single-mode cavity.